A today predominant continuous metal extruding machine, or simply metal extruder, of rotary extrusion type, well known in the art, is manufactured by the company H. Folke Sandelin® and marketed under the trademark HANSSON-ROBERTSON®.
U.S. Pat. No. 3,693,394 discloses one example of a HANSSON-ROBERTSON® type of metal extruder. A conventional HANSSON-ROBERTSON® machine comprises a main motor, a gear box, an extrusion screw, a screw housing, screw bearings, a bearing housing, a die block, temperature control means, a melting pot and a feed pipe. The main motor and gear box are arranged to drive and rotate the extrusion screw inside the screw housing. The screw is rotatably supported in the bearing housing and extends from the bearing housing towards the die block. Melted metal is arranged to be fed, via the feed pipe, into the screw housing to fill spaces between the outer surface of the screw and the inner surfaces of the screw housing. The temperature control means enables control of the temperature of the metal in the screw housing, i.a. so that it can be transported by the screw (typically be keeping the metal in plastic state), and to allow for control of the extrusion process, and thereby, in the end, also quality of the extruded product. The rotation of the screw transports the metal towards the die block under high pressure and the screw terminates at an inlet to the die block. For extrusion into cable sheet, the die block comprises means for turning the flow of the metal, typically plastic lead, 90-degrees, so that the flow direction becomes substantially perpendicular to the axial (metal transport or extrusion) direction of the screw, thereby enabling forming the cable sheet onto a cable being transported in the perpendicular direction through the die block.
Extrusion of metals requires considerably pressure to force the metal through the die block in a desirable manner. For example, in the case of lead extrusion, the pressure is in the order of 1700 atmospheres, and in the case of aluminum, in the order of about 5000 atmospheres. For operation of the machine at such high pressure, the extrusion screw of a HANSSON-ROBERTSON® extruder is axially supported by a thrust bearing in the bearing housing, typically arranged in the axial direction between a radial protrusion of the screw and the bearing housing. Such thrust bearing is e.g. shown in FIG. 1 of U.S. Pat. No. 3,693,394.
Hitherto, all HANSSON-ROBERTSON® type of machines have been designed to be vertically oriented during operation, i.e. so that the screw extends vertically, i.e. aligned with gravity, with the metal being transported upwards. However, one problem with a vertical oriented machine is that a large part of the machine, e.g. the motor, gearbox, bearing housing, and a large part of the screw and screw housing, have to be placed below floor level in the production plant where the machine is to be operated. Reason for this is that it is desirable, or even required, to have the die block and the output of the extruded product at a level not too far above the floor level of the plant. As a result, a costly, both in time and money, deep foundation has to be prepared in the floor of the plant before a machine can be installed.